Self cleaning rock drill bit



Dec. 5, 1961 o. DE BREE ETAL 3,011,571

SELF CLEANING ROCK DRILL BIT Filed Jan. 23, 1961 INVENTOR5.OSCAR-L-DEBREE PAUL J' BOU DREZ ATTORNE Y United States Patent 3,011,571SELF CLEANING ROCK DRILL BIT Oscar L. De Bree, 1200 Penufield Road, andPaul J. Boudrez, 334 Titus Ave., both of Rochester, N.Y. Filed Jan. 23,1961, Ser. No. 84,167 2 Claims. (Cl. 175-413) This invention relates toa rock drill bit, and more particularly to a drill bit having provisionfor continuous self cleaning during the drilling operation.

Rock drill bits used in conjunction with pneumatic hammers have beenproposed in which compressed air from the hollow drill rod is dischargedthrough the bit face, in an effort to cause the rock chips to be drivenupward along the drill rod. The presence of air ports in the face of thedrill bit presents a problem in that such ports may readily becomeplugged with rock chips, despite the pressure of the air stream. Thesmall diameter of the ports in the face of the bit, is such that onceplugged, the air pressure supplied to the hollow drill rod isinsuificient or ineffective to unplug the ports.

The present invention is directed to a drill bit, in which there isprovided one or more ports, directed away from the cutting face of thebit. The invention is further directed to a drill bit of unitaryconstruction, and in which air blast ports are directed away from thecutting operation so as to be protected from being plugged by thecuttings and force of the hammer action of the drill bit tending toforce the cuttings into the ports.

A primary object of the invention is to provide a drill bit capable ofdrilling through a sequence of rock, stone, and earth overburden at afast rate of speed without necessity for changing bits when passing fromearth overburden to rock drilling, and in which the self cleaning actionremains efiective at all times, by reason of the air blast beingdirected rearwardly of the cutting face where it is protected from beingplugged by chips or earth which would be driven into the air dischargeports if located in the cutting face of the drill.

A further object of the invention is to provide a new and improved drillbit, in which air is forced down the hollow drill rod and through airpassages in the bit and emitted out of the top of the bit, or rearwardlyof the direction of the drilling operation. The air action, dischargingrearwardly provides an air lift or suction below the discharge whichdraws the rock chips or earth into the blast, whence the drillings areblown up the annular passage formed by the drilled hole around the drillrod and discharged from the hole entrance.

A still further object of the invention is to provide a drill bit thatwill pulverize rock and which will continue to remain efiicient throughlong periods of use Without becoming clogged, or necessitatingregrinding of the cutting facets.

The above and other objects of the invention will appear more fullyhereinafter from the following detailed description when taken inconjunction with the accompanying drawings. It is expressly understoodthat the drawings are employed for purposes of illustration only and arenot designed as a definition of the limits of the invention, referencebeing had for this purpose to the appended claims.

In the drawings, wherein like reference characters indicate like parts:

FIGURE 1 is a top or rear plan view of the drill bit, as viewed from theline 11 of FIGURE 2;

FIGURE 2 is a side elevation of the drill bit;

FIGURE 3 is an end view of the cutting face; and

FIGURE 4 is a longitudinal sectional view through the drill bit, takenon the line 44 of FIGURE 1.

Referring to the drawings there is shown a rock drill bit mounted on theend of a drill rod 22 that is driven by a pneumatic hammer. The drillrod is rotated in the direcice tion of the arrow A, during hammeroperation, and is provided with a left hand thread 24, engaging with acorresponding thread 26 in the sleeve portion 28 of the bit. The bit isformed of drill steel, and transverse slots 30 and 32 are milled in theend to receive hardened elements 33 of such material astungsten-carbide.

After milling the slots, air discharge passages 34 and 36 are drilled inthe sleeve portion, and primary air passages 38 and 40 disposed radiallyinward thereof are drilled, and the intervening metal milled away as at42, to provide interconnections between the passages 34 and 33, and 36and 40 respectively. The bit head is preferably of steel, cast ormachined, to form the general outline shown, and after completion of themachining operations including drilling and milling, the head is air orWater hardened, following which the cutting elements 33 are silver orcopper brazed in their respective slots, the elements 33 overlying themilled slots 42 serving to form a closure for the interconnectionsbetween the ports 38 and 40, and 34 and 36 respectively.

The cutting facets 33 are provided with cutting edges 35, and theadjacent cutting facets, are provided with intervening relief channels31, for the upward passage of the pulverized rock, rock chips and earth.It will be seen that a heavy blast of air being supplied to the hollowdrill rod during the drilling operations, a blast of air is continuouslyemitted upward and rearwardly of the drilling operation from the ports34 and 36. Such blast creates a suction in the channels 31, drawing theearth, cuttings and the like continuously from the bit face, and thecutting action taking place thereat, and once the drillings rise to theregion above the blast of the ports 34 and 36, the drillings are drivenup the annulus formed by the hole being drilled and the drill rod 22.The continuous removal of the drillings leaves the drill bit cuttingface clear to act upon the uncut rock in the end of the bore, andehminates wasted effort tending to grind up chips already cut loose,with the result that the bit remains sharp over long periods of time.

Employing air discharge ports which open to the rear of the cutting faceeliminates the tendency which would otherwise eXist of driving, by thehammering action, chips and the like into the ports with a constanttendency of the plugging thereof. The drill bit, as described isessentially a one piece rigid and hardened sleeve with its grooves toreceive the cutting elements, and by the fabrication of the sleeve inthe manner described, the tortuous passage for the air blast is easilyformed at low cost, with the closure of the interconnecting milled slots42 being eiiected by the brazing or otherwise bonding in place of thecutting blocks 33. i

There is thus provided a solid rugged bit having long life and capableof rapid drilling operation through sequences of widely varying rockstrata, without interruption due to plugging.

While a single form of the invention is shown, it is to be understoodthat the invention is not limited thereto. As various changes in theconstruction and arrangement may be made without departing from thespirit of the invention, as will be apparent to those skilled in theart, reference will be had to the appended claims for a definition ofthe limits of the invention.

What is claimed is:

l. A pneumatic drill bit comprising a one piece head and sleeve, saidsleeve being internally threaded to receive a hollow drill rod, and saidhead having radial slots in its face to receive cutting elements, an airdischarge port extending from a radial slot lengthwise through thesleeve and a primary air port extending from the same slot and extendingthrough the head and located radially inward of said first named portand within the inside sleeve wall, a radial connecting passage formed inthe base of the slot and connecting said discharge and primary ports,and a cutting element disposed in said slot and forming a closure forsaid connecting passage.

2. A pneumatic drill bit comprising a one piece head and sleeve, saidsleeve being internally threaded to re ceive a hollow drill rod, andsaid head having four uniformly spaced radial slots in its face toreceive cutting elements, air discharge ports extending from two of saidopposed radial slots lengthwise through the sleeve and primary air portsextending from the same slots and extending through the head and locatedradially inward of said first named ports and within the inside sleevewall, radial connecting passages formed in the base of the said two ofthe slots and connecting said respective discharge and primary ports,and cutting elements disposed in said slots and forming a closure forsaid connecting passages in said two of said slots.

References Cited in the file of this patent UNITED STATES PATENTS2,022,194 Galvin Nov. 26, 1935 2,085,941 Arnold July 6, 1937 2,101,865McCallum Dec. 14, 1937 2,485,098 Johnson Oct. 18, 1949 2,522,045 KnowlesSept. 12, 1950

